block/drbd/drbd_interval.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <asm/bug.h>
0003 #include <linux/rbtree_augmented.h>
0004 #include "drbd_interval.h"
0005
0006 /*
0007  * interval_end  -  return end of @node
0008  */
0009 static inline
0010 sector_t interval_end(struct rb_node *node)
0011 {
0012     struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb);
0013     return this->end;
0014 }
0015
0016 #define NODE_END(node) ((node)->sector + ((node)->size >> 9))
0017
0018 RB_DECLARE_CALLBACKS_MAX(static, augment_callbacks,
0019              struct drbd_interval, rb, sector_t, end, NODE_END);
0020
0021 /*
0022  * drbd_insert_interval  -  insert a new interval into a tree
0023  */
0024 bool
0025 drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
0026 {
0027     struct rb_node **new = &root->rb_node, *parent = NULL;
0028     sector_t this_end = this->sector + (this->size >> 9);
0029
0030     BUG_ON(!IS_ALIGNED(this->size, 512));
0031
0032     while (*new) {
0033         struct drbd_interval *here =
0034             rb_entry(*new, struct drbd_interval, rb);
0035
0036         parent = *new;
0037         if (here->end < this_end)
0038             here->end = this_end;
0039         if (this->sector < here->sector)
0040             new = &(*new)->rb_left;
0041         else if (this->sector > here->sector)
0042             new = &(*new)->rb_right;
0043         else if (this < here)
0044             new = &(*new)->rb_left;
0045         else if (this > here)
0046             new = &(*new)->rb_right;
0047         else
0048             return false;
0049     }
0050
0051     this->end = this_end;
0052     rb_link_node(&this->rb, parent, new);
0053     rb_insert_augmented(&this->rb, root, &augment_callbacks);
0054     return true;
0055 }
0056
0057 /**
0058  * drbd_contains_interval  -  check if a tree contains a given interval
0059  * @root:   red black tree root
0060  * @sector: start sector of @interval
0061  * @interval:   may not be a valid pointer
0062  *
0063  * Returns if the tree contains the node @interval with start sector @start.
0064  * Does not dereference @interval until @interval is known to be a valid object
0065  * in @tree.  Returns %false if @interval is in the tree but with a different
0066  * sector number.
0067  */
0068 bool
0069 drbd_contains_interval(struct rb_root *root, sector_t sector,
0070                struct drbd_interval *interval)
0071 {
0072     struct rb_node *node = root->rb_node;
0073
0074     while (node) {
0075         struct drbd_interval *here =
0076             rb_entry(node, struct drbd_interval, rb);
0077
0078         if (sector < here->sector)
0079             node = node->rb_left;
0080         else if (sector > here->sector)
0081             node = node->rb_right;
0082         else if (interval < here)
0083             node = node->rb_left;
0084         else if (interval > here)
0085             node = node->rb_right;
0086         else
0087             return true;
0088     }
0089     return false;
0090 }
0091
0092 /*
0093  * drbd_remove_interval  -  remove an interval from a tree
0094  */
0095 void
0096 drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
0097 {
0098     rb_erase_augmented(&this->rb, root, &augment_callbacks);
0099 }
0100
0101 /**
0102  * drbd_find_overlap  - search for an interval overlapping with [sector, sector + size)
0103  * @root:   red black tree root
0104  * @sector: start sector
0105  * @size:   size, aligned to 512 bytes
0106  *
0107  * Returns an interval overlapping with [sector, sector + size), or NULL if
0108  * there is none.  When there is more than one overlapping interval in the
0109  * tree, the interval with the lowest start sector is returned, and all other
0110  * overlapping intervals will be on the right side of the tree, reachable with
0111  * rb_next().
0112  */
0113 struct drbd_interval *
0114 drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
0115 {
0116     struct rb_node *node = root->rb_node;
0117     struct drbd_interval *overlap = NULL;
0118     sector_t end = sector + (size >> 9);
0119
0120     BUG_ON(!IS_ALIGNED(size, 512));
0121
0122     while (node) {
0123         struct drbd_interval *here =
0124             rb_entry(node, struct drbd_interval, rb);
0125
0126         if (node->rb_left &&
0127             sector < interval_end(node->rb_left)) {
0128             /* Overlap if any must be on left side */
0129             node = node->rb_left;
0130         } else if (here->sector < end &&
0131                sector < here->sector + (here->size >> 9)) {
0132             overlap = here;
0133             break;
0134         } else if (sector >= here->sector) {
0135             /* Overlap if any must be on right side */
0136             node = node->rb_right;
0137         } else
0138             break;
0139     }
0140     return overlap;
0141 }
0142
0143 struct drbd_interval *
0144 drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
0145 {
0146     sector_t end = sector + (size >> 9);
0147     struct rb_node *node;
0148
0149     for (;;) {
0150         node = rb_next(&i->rb);
0151         if (!node)
0152             return NULL;
0153         i = rb_entry(node, struct drbd_interval, rb);
0154         if (i->sector >= end)
0155             return NULL;
0156         if (sector < i->sector + (i->size >> 9))
0157             return i;
0158     }
0159 }